To what extent does a reduction in animal protein intake impair the fulfillment of all other nutrient-based recommendations? According to a new study published in The Journal of Nutrition, the lowest animal protein share in total proteins compatible with nutritional adequacy taking into account affordability and eating habits varies from 45% to 60% depending on the group of adults considered.
Higher consumption of plant-based foods has been associated with positive health outcomes, whereas excess consumption of red meat and processed meat is often discouraged by public health guidelines. Because meat has a higher protein content per kilocalorie than plant-based foods, shifting towards more plant-based diets and less meat can reduce both total dietary proteins and the animal protein contributions to overall nutrient intakes.
To determine the extent to which decreases in protein intakes from animal-based sources allows the achievement of nutritional adequacy, Florent Vieux (MS-Nutrition) and colleagues utilized a French, cross-sectional representative survey for 5 French subpopulations: 1) women <50 years; 2) women 50-64 years; 3) women > 65 years, 4) men < 65 years; and 5) men > 65 years. Mathematical modeling was used to assess the minimum protein level (model set #1) and the minimum animal protein contribution to total proteins (model set #2) that are compatible with the fulfillment of all nutrient-based recommendations. Eating habits were considered in model set #2 only. Diet cost was constrained to not exceed the observed cost, because without that constraint, very expensive foods were introduced in the modeled diets.
The minimum amount of protein that was theoretically compatible with the fulfillment of non-protein nutrient-based recommendations (model set #1) was below the minimum recommended protein intake for all subpopulations except women < 50 years of age. In model set #2, for women and men > 65 years of age, decreasing animal protein contributions to total proteins below 55% and 60%, respectively, led to protein levels below recommended levels. For the other subpopulations (women < 50 years, women 50-64 years, and men < 65 years), the lowest animal protein contributions to total proteins compatible with a nutritional adequate diet (including protein adequacy) were 55%, 50%, and 45%, respectively.
Collectively, study results showed that when total proteins were directly minimized without considering eating habits, a strict minimum of at least 48 grams of protein per day of total proteins was needed to meet nutrient-based recommendations for nutrients other than proteins. Animal proteins could be reduced to contributions that were between 45% and 60%, depending on age and sex, while still being compatible with complete nutritional adequacy and affordability. In diets with reduced animal protein contributions, the most difficult recommended nutrient levels to achieve were for vitamin D, zinc, fiber, alpha-linolenic acid, and saturated fatty acids in all subpopulations and for iodine, calcium, magnesium, and total sugars in some subpopulations.
Florent Vieux, Didier Rémond, Jean-Louis Peyraud, Nicole Darmon, Approximately Half of Total Protein Intake by Adults Must be Animal-Based to Meet Nonprotein, Nutrient-Based Recommendations, With Variations Due to Age and Sex, The Journal of Nutrition, Volume 152, Issue 11, November 2022, Pages 2514–2525, https://doi.org/10.1093/jn/nxac150.
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